Absorbent articles, such as sanitary napkins, panty liners, and incontinence pads that are designed to absorb and retain liquids and other discharges from the human body and to prevent body and clothing soiling, having various different constructions are well known.
The current tendency has been to develop absorbent articles such as sanitary napkins which are increasingly thinner and conform better to the body. Recently, efforts have been directed to developing thinner sanitary napkins which have the capacity to absorb and contain medium to high menstrual discharges. Previously, such discharges could only be handled by relatively thick sanitary napkins. Examples of thin sanitary napkins having capacities great enough to handle medium to high menstrual flows are disclosed in U.S. Pat. Nos. 4,950,264 and 5,009,653, issued to Osborn, on Aug. 21, 1990 and Apr. 23, 1991, respectively.
One of the main objectives in developing absorbent articles is to utilize the entire capacity of the absorbent article. The utilization of the capacity for absorption of menses and other bodily exudates in the thin sanitary napkins described in the Osborn references is achieved at least in part by the presence of a "wipe acquisition sheet" that distributes the exudates more evenly over the underlying absorbent core. In general, products that are not provided with a structure like the wipe acquisition sheet described in the aforementioned patents, typically distribute liquids in a circular pattern, resulting in liquids reaching the longitudinal side edges of the absorbent article before the end regions of the absorbent article are utilized. When liquids come near the longitudinal side edges of the absorbent article, the chance for leakage from the sides of the product increases, despite available absorbent capacity in the end regions of the absorbent article. Even if the absorbent capacity of the end region is more fully utilized, a signal that the absorbent capacity of the absorbent article is being approached is desirable to users in order that the user may change the article before leakage and resultant staining can occur. Further, users have shown a preference for absorbent articles having a clean and dry appearance, even after much of the absorbent capacity of the absorbent article has been used.
In the past, a number of efforts have been made to direct exudates in an attempt to utilize more of the absorbent capacity of an absorbent article. A number of these efforts have used absorbent means or densification of absorbent means. Some of such efforts are described in U.S. Pat. No. 4,678,453 issued Jul. 7, 1987 to Holtman and U.S. Pat. No. 4,624,666 issued Nov. 25, 1986 to DeRossett, et al. Absorbent articles which use absorbent means to direct fluid flow, however, are typically subject to the disadvantage that the absorbent means will tend to become saturated and interfere with its fluid directing capabilities.
Another series of patents teaches the use of baffles, barriers, and transfer members for liquid transport. For instance, U.S. Pat. No. 4,029,101 issued Jun. 14, 1977 to Chesky et al. discloses using an elongated baffle near the base of the pad. U.S. Pat. No. 3,736,931 issued Jun. 5, 1973 to Glassman discloses using a moisture impervious layer in the pad. However, in both of these examples, liquids may wick laterally before reaching the baffle or the moisture impervious layer. This may tend to cause side failure (or side leakage), particularly when the pad bunches during wear. In such cases, the barrier or transfer member may be disturbed by the bunching of the pad, and body fluids may circumvent the barder or transfer member and flow directly toward the longitudinal side edges of the product.
Attempts have also been made to provide a signal that it is time to change the article. For example, U.S. Pat. No. 5,401,267 issued to Couture-Dorschner on Mar. 28, 1995 describes an absorbent article having first and third members with a high wicking capacity and a second member with a lower wicking capacity. The second member has a width equal to or greater than either of the first or third members and is said to provide a visual signal that it is time to change the article when it appears to be soiled. However, the first member thereof lies immediately below the cover sheet so the body contacting surface of such an absorbent article may appear to be soiled, even with unused absorbent capacity.
Thus, a need exists for an absorbent article, such as a sanitary napkin that has an improved means for drawing bodily exudates from the surface thereof and distributing the exudates so that the exudates will not reach the longitudinal side edges of the absorbent article before the absorbent capacity of the absorbent article is substantially exhausted, thus maintaining a relatively clean appearance for the majority of the wear cycle of the absorbent article.
It is, therefore, an object of the present invention to provide an absorbent article, such as a sanitary napkin, with a means for drawing fluid from the surface to the middle of the absorbent article and for insuring the absorbent capacity of the sanitary napkin is substantially exhausted before liquids reach the longitudinal side edges of the napkin.
It is another object of the present invention to provide a signal to a user that the absorbent capacity of the absorbent article is substantially exhausted and that it is time to change.